1. Field of the Invention
The invention relates to a laser device or double buried heterostructure optical guide amplifier and a simple method for the monolithic integration of this device into complex photonic circuits.
A device of this kind is very useful, especially for the making of complex integrated optical circuits used in integrated optics or optical telecommunications for example.
2. Description of the Prior Art
Up until now, many different approaches have been envisaged for the making of laser devices or buried structure optical amplifiers integrated into photonic circuits. In every case, the manufacturing methods are complex and require several epitaxial operations, namely at least three epitaxial operations and/or specific epitaxial operations such as localized epitaxy for example.
Furthermore, although the performance characteristics of the active components, namely the lasers or amplifiers made according to existing methods, are generally good, those of optical guides are often inadequate, so much so that they dictate a limiting of the size of the integrated optical circuits. Finally, the quality of the coupling between two optical functions varies hugely depending on the methods used.
A recent article, "Taper-waveguide integration for polarization insensitive InP/InGaAsP based optical amplifiers", Electronics Letters, Apr. 08, 1994, Vol. 30, No. 16, describes a simple technique for the integration of an amplifier with an optical waveguide designed to facilitate coupling with an optical fiber.
However, this device has a guiding layer with an extremely small thickness in the range of 0.04 micrometers (.mu.m), enabling a very low confinement factor to be obtained. The device therefore has a deconfined mode enabling it to be coupled to an optical fiber. Furthermore, the optical guide has high optical losses due to the absorption of p type free carriers which are elements for the doping of the InP layers. However, to make integrated photonic circuits, it is necessary to make devices having a highly confined mode and low optical losses. For this reason, the device described in this document cannot be usefully adapted to the making of photonic circuits.
All the currently existing methods, which make use of simple technology, therefore do not enable the making of devices that simultaneously possess high performance values for two different optical functions: there is always a compromise to be made between the performance characteristics of the two integrated optical functions, to the detriment of the quality of the guides. However, there are other methods that can be used to obtain devices with high performance characteristics for two different optical functions. But these methods make use of very complex technologies implementing three to five epitaxial operations so much so that it is quite difficult to obtain the required devices. consequently, the devices manufactured up till now cannot be used to obtain, in a simple way, complex integrated photonic circuits comprising elements such as turns, intersections or Y-shaped connections, for example.